How to effectively prevent warping and deformation of solid wood panels

How to effectively prevent warping and deformation of solid wood panels

In recent years, in the manufacturing of solid wood furniture, large-sized components are often made of solid wood panels made of solid wood narrow boards and small pieces of glue, which can not only alleviate the shortage of supply and demand of high-quality solid wood resources, but also meet the growing market demand for solid wood and its products.

  1. Solid wood patchwork process flow

Solid wood panels are prone to quality problems such as warpage, deformation, cracking and so on. This paper analyzes the main factors affecting the quality instability of solid wood panels, summarizes the methods to improve the stability of solid wood panels, so as to solve the quality problems such as warpage and deformation of solid wood panels.

How to effectively prevent warping and deformation of solid wood panels! (original)

How to effectively prevent warping and deformation of solid wood panels! (original)

  1. Common quality problems of solid wood panels

At present, there is no corresponding solid wood panel standard in China. Most enterprises and users pay more attention to the appearance of solid wood panels, and lack inspection standards and management methods for quality problems such as surface warping and deformation, glue layer cracking, finger tenon falling off and fracture.

Many enterprises often use simple repair methods to cover up, which has affected the development of the solid wood panel industry to a certain extent. Therefore, how to ensure shape stability and reduce deformation is the key to improve the quality of solid wood panels.

How to effectively prevent warping and deformation of solid wood panels! (original)

How to effectively prevent warping and deformation of solid wood panels! (original)

How to effectively prevent warping and deformation of solid wood panels! (original)

  1. Factors affecting the dimensional stability of solid wood panels

3.1 wood factor

Wood will crack and deform without external force, which is mainly caused by the internal stress in the wood. In addition to the internal stress of the wood unit itself, the internal stress in the solid wood panel also includes the stress between the wood units – the internal stress generated in the panel process. These are related to the density, moisture content, surface roughness, splicing method, glue type, gluing amount, gluing pressure, temperature and humidity in the air, etc.

How to effectively prevent warping and deformation of solid wood panels! (original)

How to effectively prevent warping and deformation of solid wood panels! (original)

3.2 gluing amount

When the glue amount is too low, there will be glue shortage and uneven distribution of adhesive; When the amount of adhesive is too high, the adhesive layer is too thick. When the adhesive layer is cured, the volume shrinkage will produce internal stress, which will destroy the cohesion of the adhesive and reduce the bonding strength.

How to effectively prevent warping and deformation of solid wood panels! (original)

How to effectively prevent warping and deformation of solid wood panels! (original)

3.3 gluing pressure

Pressurization is conducive to the full penetration of the glue, so that the glue combines with the active molecules of wood to form a uniform glue film. However, improper pressure is easy to extrude the glue, resulting in glue shortage and penetration. At the same time, higher pressure will seriously deform the material and form greater stress.

How to effectively prevent warping and deformation of solid wood panels! (original)

How to effectively prevent warping and deformation of solid wood panels! (original)

It can be seen that eliminating the internal stress of materials and improving the dimensional stability of solid wood panels can start from the aspects of raw materials and processes.

  1. Methods to improve the dimensional stability of solid wood panels

Based on the above reasons, corresponding measures can be taken according to the actual situation in the aspects of batching, moisture content control, gluing amount and gluing pressure to improve the quality of solid wood panels. Through the preliminary research, it is found that the following points can be improved:

3.1 reasonable ingredients

When making solid wood panels, try to use the same tree species or the air dry density difference should not exceed 0.2g/cm ³ Try to avoid wood with large difference in density and shrinkage, so as to reduce the internal stress of the plate. Because the wood is an anisotropic material, and the radial moisture absorption deformation is smaller than that in the chord direction, the chord and radial textures of adjacent narrow strips should be reasonably matched during splicing to avoid excessive chord direction wood.

How to effectively prevent warping and deformation of solid wood panels! (original)

How to effectively prevent warping and deformation of solid wood panels! (original)

3.2 control water content

The final moisture content of narrow solid wood boards should be controlled according to the moisture content of the place where the products are used before splicing. Some studies have shown that when the moisture content of wood is controlled at 5%~10%, the bonding strength is the highest. At the same time, special attention should be paid to the moisture content difference of the narrow strips of adjacent panels should not be too large. Generally speaking, controlling the deviation of wood moisture content within 2% can effectively reduce the drying shrinkage stress of wood.

How to effectively prevent warping and deformation of solid wood panels! (original)

How to effectively prevent warping and deformation of solid wood panels! (original)

3.3 use the appropriate amount of glue

During the curing process of adhesive, the bonding layer will produce shrinkage and internal stress, which will reduce the bonding strength, and the greater the amount of glue, the more obvious the internal stress. Generally speaking, the amount of single-sided gluing can be controlled within 180~300g/ ㎡, while the amount of double-sided gluing is within 140~220g/ ㎡.

3.4 adopt reasonable gluing pressure

Research shows that the gluing pressure of hard wood panels should be controlled at about 10~15kg/c ㎡, while that of soft wood should be controlled at about 5~10kg/c ㎡. At the same time, in order to prevent the solid wood narrow board from warping or bulging during gluing, a pressure of 0.1~0.2mpa is often applied on the side of the gluing direction.

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